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by Craig Shallahamer Get the book here |
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Craig Shallahamer's Blog
The text below is an except from the book, Oracle Performance Firefighting, written by Craig Shallahamer of OraPub, Inc. Figures and tables are not included on this page, only their reference. To order the book in either print or PDF form, click here. ©2009, 2010 by Craig Shallahamer. This is copyrighted material. Please—Out of respect for those involved in the creation of the book and also for their familes, we ask you to respect the copyright both in intent and deed. Thank you. ------------------------------- Figure 6-23. This is an operating system trace of an Oracle Database 11g database writer on a very idle system. Notice the 3-second database writer sleep is induced by a semaphore call. This allows the database writer to be woken if necessary. Figure 6-24. This is an operating system trace of an Oracle Database 11g database writer on a very DML-intensive system. No lines where removed between the write system call (pwrite64). Notice the database writer made a variety of different-sized writes. There are a variety of database writer-related wait events. One way to categorize the contention situation is to understand if the database writer is having "push-to-disk" issues or "pull-from-write-list" issues. Most of the issues are pushing-that is, writing to disk issues. But there is a very common pull situation that I'll detail in the next section. Please—Out of respect for those involved in the creation of the book and also for their familes, we ask you to respect the copyright both in intent and deed. Thank you. |
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